Bam! You nailed it. Now I finally understand why I only see the splash screen once in a while. I just checked this by letting the car sit so that the nav shuts down completely. Then I quickly opened the door, got in and turned on the ignition. The screen opened and I saw the splash screen. Thanks Jochen for explaining this!

As for the other suggestion for manually opening the screen, unfortunately it did not work. It seems that the X3 screen only works with the ignition on. If I manually flip up the screen when the ignition is off and open the door to get the nav to cold boot, I see nothing on the screen. Turning the ignition on makes the screen go down, then back up. If I'm quick, I can get a glimpse of the splash before the annoying accept screen.